Musical instrument



Nov. l2, '1929. w, 1 KREBs f 1,734,973

MUSICAL INSTRUMENT Filed June 27, 1925 5 Sheets-Sheet l w.' TML.

Nov. 12, 1929. w. J. KRr-:Bs l 1,734,973

MUSICAL INSTRUMENT Filed June 27, 1925 3 Sheets-Sheet 2 No'v. 12, 1929. w. J. KREBs MUSICAL INSTRUMENT Filed June 27, 1925 3 Sheets-Sheet 5 Patented Nov. 12, 1929 PATENT OFFICE WILLIAM J. KREBS, OF DAYTON, OHIO lMUSICAL vINSTRTJIVIENT Application filed .Tune l27,

The invention relates to pneumatically ac-v tuated musical instruments of the type which consist generally of pneumatic tone-producing actions, a main source of power for actuating the same, and mechanism in the air connection between the main source of power and the tone-producing actions to control the expressions produced'by the latter.

The invention relates more particularly to the mechanism, or expression actions, for controlling the expression produced by such instruments and it is an object to provide suoli mechanism which is simple in construction, reliable in operation, and capable of responding quickly to produce the most delicate expressions in the playing ofthe automatic musical instrument with which it is associated.

A further object of the present invention resides in the provision of such mechanism capable of operating with the minimum number of expression holes in the cooperating trackerfbar and music sheet of such musical instruments.

To these and other ends the invention resides in the novel features of construction,` arrangement of parts, and combination `of elements hereinafter described.

Of the Vvarious embodiments of which the invention is capable, there is selected for description `and specific illustration herein the one which at the present time is believed to exhibit the invention in its most convenient.- and effective form. This embodiment is illustrated in the accompanying drawings, in which,

Fig. 1 is a view, partly in section, showing a pneumatically actuated musical instrument embodying the present invention;

Fig. 2 is a front elevationshowing the present invention assembled as a unit;

Fig. 3 is a side elevation of 4a portion of Fig. 2, part of the apparatus being broken away to show details of construction;

Figs. 4f and 5 are details of the valve shown in Fig. 2; and

Figs. 6, 7, 8, and 9 are diagrammatic views showing operating positions of the mainv valve.

Referring to Fig. 1, reference character 10 pump channel 1923. Serial No. 648,136.

designates a pump adapted to exhaust air from the high exhaust chest or pump channel 11, which in turn is connected with wind or regulated pressure chest 12 through the air connection or tube designated as a whole by 13. Tracker bar 15 is provided with openings or ducts 15a adapted to cooperate with a perforated music sheet in the well known manner.k The ducts 15L are connected to any suitable known type of tone-producing actions which are connected with and adapted to be operatedrfrom the wind chest 12 in a manner well understood by those 'skilled in the art. The. pump 10 constitutes a main source of power for actuating the tone-producing actions which are connected with wind chest 12 and controlled by the ducts 15a.

The tone-producing action illustrated includes a typical. key action which is shown in its normal position of rest. When the key 1 is struck it elevates a sticker 2, rocking a hammer 3 and causing the latter to strike a string l, at the same time withdrawing from the string a damper 5. This same operation may be effected automatically as by means of a motor pneumatic 6, controlled from the tracker board 15, as hereinafter described, which acts through the medium of a sticker 7 to elevate a rocker 8 controlling the hammer 3. The motor pneumatic is connected with chest 12 through a trunk 9, and with a tracker board vent 15athrough a conduit 15b. This tone producing action is merely illustrative of one form and is not intended as limiting the present invention in any way.

Interposed in the air connection 13 is a main valve designated as a whole by 14 consisting generally of a stationary valve member or guide 15 and movable valve members or elements 16 and 17, the former being operated by expression bellows 18 and the latter being operated by regulating bellows 9. The movable valve members are slidable in a vertically disposed circular guide or chamber which serves as an air passage, having a branch 19 at the side thereof for connection with the wind chest 12 and a branch 2O at the lower end thereof for connection withthe 11. Air entering at the branch 19 passes between the cooperating edges of the movable valve members 16 and 17, thence downwardly through hollow valve member 17, and then through branch 20 to the pump 10 by which it is exhausted.

Valve member` 16 consists of a light hollow tube closed at its upper end by means of felt, cork or other light material 21 preventing the entrance of air into the valve at the top. Rigid rod 22 is pivotallysecured to valve member 16 by means of a pin 23 or other suitable connection and serves as a stem or lifter by which the valve 16 may be lifted.

Rigidly secured on lifter rod 22 are a plurality of buttons 24 which form shoulders adapted to be engaged by-the rmovable arms 25 of expression bellows 18. As shown in Figs. 1 and 2 there are four buttons on the lifter rod 22, each adapted to be engaged by the movable arm 25 of an expression bellows. As shown in Fig. 2, the rod 22 passes slidably through a forked aperture in the arm 25 with the button 24 resting on a washer of suitable sound-deadening material carried in the aperture. The movable valve member 16 is illustrated in its lowest position with a button resting on the -movable arm 25 of each bellows 18a, 18h, 18e and 18d. lThe suction due to the partial vacuum within the valve draws the valve 16 downwardly and'holds each of these expression'bellows fully distended, as illustrated. vTo raise the valve 16 one of the expression bellows must be exhausted or collapsed. When bellows 18a, for example, is exhausted, the arm 25 moves upwardly but a short distance until it strikes-the adjustable stop 26, and the lifter rod and valve 16 are lifted a correspondingly short distance. Bellows 18"*and 18C lift the valve 16 successively greater distances, the exact amounts being determined by the adjustment of the stops 26b and 26C. Bellows 18d collapses fully when it is exhausted and liftsthe valve the maximum amount. This bellows is provided with an adjustable stop 26d to limit the 'lowest position or minimum opening of the valvey 16. This is the pianissimo position of the valve members. The positions of valve 16 produced by the collapse of expression bellows 18a, '18", 18C, and 18d correspond respectively tothe piano, mezzo forte, forte, and fortissimo expressions, and are illustrated in Figs. 6,7, 8, and 9.

The expression bellows v,are exhausted through the ducts 27, 28, 29,7andv 3,0 controlled bythe four pneumatic actions or valves 31 which are identical lin construction as illustrated in Fig. 1. The pneumatic actions are mounted in a single block 32 and have a common wind channel 33. As showninFig. 2, the block 32 `is mounted-adjacent the main valve 14on the base 49, the air connectionor tube 13 passing through the block v32 and communicating with the wind channel 33 therein. The four pneumatic actions have chambers 34 communicating with the respective ducts 27, 28, 29, and leading to the expression bellows, and have compartments 35 communicating through ducts 36, 37, 38, and 39 with the tracker bar, as illustrated in Fig. 1. Compartment 35 has a flexible diaphragm 40 having an aperture 41 through which air is lnormally exhausted from the duct leading Yto the-tracker bar. Diaphragm 40 actuates a valve rod 42 carrying a valve 43 controlling a passage from the chamber 34 to the wind channel33 and a valve 44 controlling a passage from the chamber 34 to the atmosphere.

The operation of the expression actions is as follows: Referring particularly to the piano expression which is produced by expression bellows 18, the duct 27 is normally connected through chamber 34 with the atmosphere .and the bellows 18n is therefore fully expanded, allas clearly shown in Fig. 1. Likewise, the duct 36 'is normally exhausted through the aperture 41 in diaphragm 40. To produce'the expression piano a perforation in the music sheet is caused to register withthc duct 36 in the tracker bar, whereby air rushes into duct 36 and destroys the vacuum therein. This permits diaphragm 4() toibo drawn to the right'by the suction in the wind channel 33 so that valve 44 closes the passage between chamber 34 and atmosphere and valve 43 opens the passage connecting chamber 34 with the wind channel. Air being thus exhausted from duet 27 and bellows 18a, the latter collapses as far as permitted bythe adjustable stop 26n and the valve 164 is raised tothe position shown in Fig. 6. This shows the valve opening required to produce the expression piano.

This expression is maintained so long as the duct 36 is uncovered. 711911, however, the musicsheet again covers duct 36, the air is exhausted therefrom through aperture 41 in diaphragm 40, and chamber 34 and duct 27 are connected to atmosphere with the result that bellows 18a Ais expanded and valve 16 drops to its original position unless, in the meantime, another expression action'hasbeen brought into action tolift the rod 22 and valve 16 to another position.

The valve member 16 is constantly being pulled downwardly towards its-valve-closing position by 4the action of the partial vacuum or suction within the valve, and the forcesacting on the valve member 16 are such that whenever the rod 22 is released by one ofthe bellows, the valve moves downwardly with extreme rapidity. The upward movement of the valve is very rapid due to the small cubical content of bellows 18 and the cooperating ductsI and the speed which they can be exhausted by pump 10. It will be understood that the bellows 18 lift the red 22 against the suction of the vacuum within lthe valve.

Theseveral expression actions operate seploud expression after a softerone, as for ex-` ample,

,Figz 6 to produce the already described. Uncovering,

' and `ment that such control was thereafter or may be maintained so as arately and independently of one another. By uncovering duct 36 expression bellows 18a is caused to act to open valve '16 as shown in piano expression, as separately, the ducts 37, 38, and 39 causes, in the same manner, the actuation of expression bellows 18", 18, and 18c1 to open valve 16 as shown in Figs. 7, 8, and 9 to produce mezzo forte, forte,

fortissimo, respectively. Each expression bellows operating independently of all the others, produces its predetermined expression. Should it be desired to produce a forte after piano, then it is merely required that the duct 38 be uncovered at the desired instant, and the bellows 18C will lift the rod 22 to the proper position irrespective of bellows 18 which had control up to the motalren away by bellows 18C. A loud expression action will always taire away control of the rod 22 Aand valve 16 from a softer expression action, and the latter may be discontinued at any time to again take control of the valve when the loud expression action is discontinued.

To produce a soft expression after a louder one, the soft expression action is operated at any time before the louder one is discontinued, or concurrently therewith, so as to take control of the rod 22 and valve 16 when the rod is released by the louder action'.

- 1t will be understood that whenever one of the expression bellows is operated, the others being at the moment inoperative, the movable arms of the inoperative bellows will remain in their lowest positions as shown in Figs. 1 and 2, and the rod 22 will slide through the apertures therein, the buttons 24 being lifted out of contact with their respective arms 25. Should a second bellows then be operated to raise the rod 22 still higher, the iirst bellows being still operative,

then the button 24 will also be lifted out of contact with the arm of the said first bellows. Since the lifting movement of the first bellows is less than that of the second, it is immaterial whether it is onor off, that is, whether it is operative or inoperative, while the rod is held in raised position by the second bellows. Accordingly, if the next expression is to be that produced by the first bellows, the latter may be maintained in its on or operative position, without the expenditure of additional energy on the part of the pump, until the second bellows releases the rod 22. Rod 22 being thus released, it moves downwardly until it is intercepted by the first bellows.

The independent operation of the express sion actions whereby each is capable of pro ducing an expression without the cooperation or assistance 'of any other action has many advantages among which may be mentioned,

' as one of the most important, that the disabling of one of the expression actions is not likely to completely disable the entire expression mechanism so as to cause the musical instrument to operate in a monotone, as is the case in prior devices. for example, be disabled so as to hold the valve 16 in on or piano position, then all other bellows causing a higher lift lof rod 22 may still operate normally to produce their respective expressions.

The present invention also includes a regulating means which comprises generally regulating bellows 9 pneumatically connected through duct 44 with wind chest 12 and mechanically connected through rod 45 with regulating valve member 17, as illustrated. As is well understood by those skilled in the art, the degree of vacuum or attenuation within the wind chest 12 tends to vary constantly due to the continually varying number of tone producing actions ,connected therewith as the music sheet passes over the ducts 15a on the tracker bar. To produce a given expression the pressure in the wind chest must be maintained uniform, and this is accomplished by the regulating bellows 9. Thus, when a large number of tone producing actions are connected with the wind chest 12 at one time, and as a consequence the degree of attenuation is reduced (pressure rises in chest 12), regulating bellows 9 expands slightly under the action of spring 46 thus pulling valve 17 downwardly and increasing the valve opening so as to permit the pump 10 toexhaust the air more rapidly from the wind chest 12 and thereby maintain the proper vacuum or degree of attenuation therein. Thevalve 17 is freely slidable in the fixed valve member 15 and responds only to the action of the regulating bellows 9.

It will be understood, that when a loud expression is desired so that the valve 16 is opened wide, the pressure in wind chest 12 is less than when a softer expression is desired, and as a consequence the pressure is reduced in the regulating bellows 9. The latter responds by moving the valve member 17 upwardly, the extent of such upward motion depending on the particular expression produced. Figs. 7, 8, and 9 show the positions of the regulating valve for mezzo forte, forte, and fortissimo respectively. The illustrated positions of the valve 17 may be regarded as their normal positions for the expressions mentioned, any variation in the number of tone producing actions resulting in further slight movements of the valve17 as already explained.

The position of the movable valve member 16 is of course regulated by means of the adjustable stops 26, or otherwise, so as to provide atl all times the proper valve opening between the valve member 16 and the valve member 17. Valve members 16 and 17 are provided on their adjacentends with com- Should bellows 18,

plementary tapered edges 47. A sudden piano or mezzo-forte while valve member 17 is raised, as in fortissimo, may cause the valve members 16 and 17 to come in contact with one another owing to the great speed at which the valve 16 descends, and when this happens, the cooperating tapered edges 47 form cuting or pinching edges capable of pinching any other extraneous matter that might lodge in the valve and thus ordinarily interfere with its proper operation. In the case of shavings or similar foreign matter of a brittle or crushable nature, the pinching action is such as to break the shaving. This action of the valve members 16 and 17 has been found effective to so pinch or crush extraneous matter as to divide the same and is therefore referred to generally as a cutting action. This self cleaning feature of the valve is assisted b the fact that the valve member 17 is open at t ie bottom and thus permits the extraneous matter to readily pass through the valve and be drawn off by the pump 10.

Owing to the extent of movement of the valve members 16 and 17 with respect to branch 19 as indicated in Figs. 6 to 9, it is desirable to cut a groove 48 in the valve member 15 at each side of branch 19 as clearly shown in Figs. 4 and 5. The purpose of this groove is to facilitate the flow of air through the valve. The construction illustrated in which the air passes centrally through the valve has the advantage that the valve members are free to move without undue friction due to air pressure or other causes.

Referring particularly to Fig. 2, it will be observed that the valve 14, bellows 18 and 9, and block 32 are all mounted as a unit on a base 49. This unit is neat and compact and is particularly useful for installation in musical instruments which it may be desired to render pneumatically operable.

It will be apparent from the foregoing that the present invention provi-des a simple, cheap and reliable device capable of operating with great rapidity to produce the most delicate expressions in the playing of an automaticn'lusical instrument of the type described.

The invention as described herein in conjunction with pneumatic actions of the suction type although obviously, the same principles might be employed with pressure operated mechanism.

While the form of mechanism herein shown and described constitutes a preferred embodiment of one form of the invention, it is to be understood that other forms might be adopted and various changes and alterations made in the shape, size, and proportion of the elements therein without departing from the spirit and scope of the invention.

that is claimed is as follows:

1. In a musical instrument, in combination, pneumatic tone-producing actions; a main source of power for actuating the same including a wind passage operatively connected with the tone-producing actions; a valve in said wind passage for controlling the action of the main source of power upon the toneproducing actions; a series of three or more expression actions for controlling said valve, each such expression action being adapted, upon operation, to take away control of the valve from the preceding expression action of the series and to produce a certain expression independently of the condition of said preceding expression action.

2. An expression device for self-playing musical instruments, comprising means providing a wind passage connected at one end with the wind chest an-d at the other end with the exhauster, a valve controlling the size of the wind passage opening between the wind chest and the exhauster comprising a plurality of floating valve members adapted to cooperate with one another to! regulate the wind passage opening, an expression bellows for controlling one of said floating-valve members, and a regulating bellows connected with said wind chest for controlling the other said floating valve member.

3. An expression device for self-playing musical instruments, comprising means providing a wind passage connected at one en-d with a regulated-pressure wind chest and at the other end with an exhauster, a valve controlling said wind passage, a plurality of expression bellows operable upon said valve to control the opening of the wind passage, and a regulating bellows responsive to pressure variations in said regulated-pressure wind chest and operable at all times, to control said wind passage.

4. An expression device for self-playing musical instruments, comprising means providing a wind passage connected at one end with the wind chest and at the other end with the exhauster, a valve member controlling said wind passage and bodily movable in opposite directions to throttle or to open said passage, said valve member being so connect` ed wtih said wind passage as to be urged in one of said directions by the suction therein, and means including provisions for positively stopping said valve member in a minimumopening position and an expression bellows for moving said valve member in the opposite direction. i

5. An expression device for self-playing musical instruments, comprising means providing a Wind passage connected at one end with the wind chest and at the other end with the exhauster, a valve member controlling said Wind passage and bodily movable in opposite directions to throttle or to open said passage, said valve member being so connected with said wind passage as to be urged by the suction therein in a direction to throttle said wind passage, and a plurality of expression bellows each operable independently of the others to overcome the eiect of the suction upon said member and to move the latter to predetermine valve-opening positions.

6. An expression device for self-playing musical instruments, comprising means providing a wind passage connectedat one end with the wind chest and at the other end with the exhauster, means for controlling said wind passage comprising a valve housing communicating at one end with atmosphere and having a wind passage opening in one side wall thereof, a piston valve member guided to move in said housing and impelled by the pressure of the atmospheric air to close said side opening, and an expression bellows for moving said valve member to* wards a position to open said side opening.

7. In an expression device Jfor self-playing musical instruments, a cylindrical valve housing having a side opening adapted to be connected in a wind passage, means for controlling said passage comprising cooperating valve members in alignment with one another and guided to move Within and longitudinally oi said housing, and means for so moving said valve members.

8. In an expression device for self-playing musical instruments, a cylindrical valve housing having end and side openings adapted to be connected in a wind passage, means for controlling said passage comprising cooperating valve members guided to move within and longitudinally of said housing, one of said valve members having a longitudinal passage therein forming part of said wind passage, and means for actuating said valve members.

9. A valve for the tone governing apparatus of a musical instrument, a valve body having a vertical passage therein and a lateral inlet passage branching therefrom intermediate the ends of said vertical passage, a closed valve member slidable in the upper part of said vertical passage, a second valve member slidable in the lower part'of said vertical passage, said second valve member having a central passage therethrough, and means providing an outlet passage connected with said vertical passage below said second valve member.

10. An expression device for self-playing musical instruments, comprising means providing a wind passage connected at one end with the wind chest and at the other end with the exhauster, a valve controlling said wind passage and comprising a plurality of floating valve members adapted to cooperate with one another to regulate the wind passage opening, one of said floating members having a beveled cutting edge adapted to cooperate with the other floating member to pinch foreign matter coming therebetween.V

11. In a musical instrument, in combination, a pneumatic tone-producing action; a main source of power for actuating the same;

a valve controlling the action of the main source of power upon the tone-producing action, said valve including a movable member so constructed and mounted that it is impelled towards one direction by the direct pressure of air thereon; a plurality of expression actions for moving said movable member in an opposite direction; and a single elongated means for operatively connecting each of said expression actions with the movable member, said expression actions being distributed along the length of said elongated means and cooperating with dierent parts thereof.

12. In a musical instrument, in combination, a pneumatic tone-producing action; a main source Vof power for actuatiner the same; a valve controlling the action or the main source of power upon the tone-producing action, said valve including a movable member so constructed and mounted that it is im pelled towards one direction by the direct pressure of air thereon; three or more expression actions or moving said movable member in an opposite direction; and elongated means for operatively connecting each of said expression actions with the movable member in such manner that the operation of any one action does not cause movement of the remaining actions.

18. In a musical instrument, in combination, a pneumatic tone-producing action; a main source of power for actuating the same; a valve controlling the action of the main source of power upon the tone-producing action, said valve including a movable member; a single elongated means connected with the movable member; and a plurality of expression bellows disposed in super-imposed staggered relation about said means and connected therewith for controlling the valve.

In testimony whereof I hereto aflix my signature.

WILLIAM J. KREBS. 

